| Cyanide copper plating is one of the most widely used technologys in the conventionalcopper electroplating process, but it is very poisonous and harmful.It will affect the publicsafety and pollute the environment. So it has been banned from using it in our courntry. It hasgreat significance for the sustainable development and ecological environment protection toresearch and development a process without cyanide to replace it.In so many non-cyanidecopper plating process, HEDP copper plating process is the most likely to replace cyanidecopper plating process. Accordingly, in this paper, we researched the optimal solutioncomposition and technological conditions of HEDP copper plating system on the basis ofpredecessors’ work. Using a variety of electrochemical methods and analytical techniquesdiscussed the kinetics of copper electrodeposition.(1) The influences of different main salt in HEDP system were investigated by Hull celltest and DC electrolytic experiment. The results showed that different copper salt affected thetechnological conditions and coating performance because of the different anion.CuSO45H2Owas the best choice.The current density range of qualified coating was0~1.947A/dm2. Thegrain size was small and the copper film were smooth and dense, the adhesion to steelsubstrates was also very good. The plating speed was0.192um/min of1.0A/dm2. The currentefficiency was92.5%,(2)Effects of different kinds of additives on HEDP (1-hydroxyethane-1,1-diphosphonicacid) system （HEDP160g/L，CuSO4·5H2O40g/L，K2CO340g/L，PH9.5）was studiedby Hull cell test and DC electrolytic experiment.The results showed that the technologicalconditions and coating performance were affected by different additives. The current densityrange was enlarged to0.05~10.01A/dm2by HES and that was0~8.99A/dm2by HEA.Compounded HES and HEA could improve the radiance obviously and they could make thecoating refine and smooth, the coating brightness increased significantly. HEM could improvethe brightness of low current area.The compound additive（HEA1.5mL/L+HES3mL/L+HEM0.5mL/L+CB-10.5mL/L） accelerated the electrodeposition rate and improved cathode efficiency. The copper coating was entire bright and dense when the current density wasbetween0.24~6.70A/dm2. Deposition rate is0.210μm/min under1A/dm2.(3)The optimal bath composition and operating conditions (HEDP160g/L,CuSO4·5H2O40g/L，K2CO340g/L,HEA1.5mL/L+HES3mL/L+HEM0.5mL/L+CB-10.5mL/L,PH9.5,50℃)were obtained by DC electrolytic experiment. The current density of brighe area is0.24~6.70A/dm2. The copper coating obtained by this process is bright, dengse and smooth.(4)Studied the feasibility of barrel plating process of HEDP system.The optimal bathcomposition and operating conditions were determined: HEDP120g/L,CuSO4·5H2O16g/L，K2CO340g/L,2.0A, loading capacity50g, rotation rate15r/min, pH9.5,50℃.The resultsshowed that the composition can get the thickness of more than10μm with120min, and thecopper coating was bright and dense with good adhesion.(5)The kinetics of HEDP aqueous copper electroplating electrolyte and the influence ofadditives on cathodic polarization were investigated by polarization curves and cyclicvoltammetric curves. The results showed that the electrodeposition of Cu was a irreversible,one-step reaction.The cathode reduction mechanism may be described as follows: CuY2-+2e→Cu+Y4-.Both HES and HEA changed the cathodic polarization curves in the process ofelectroplating copper. Take HES as an example, it reduced the overpotential of electroplatingcopper and increasing the overpotential of hydrogen evolution. It improved the currentefficiency of electroplating copper. Passivation happened in the anodic oxidation processwhen used copper anode in HEDP copper plating process. |
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